Automatic telephone system



Oct. 14, 1930. N; H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM OriginalFiledsept. 17, 1927 6 Sheets-Sheet l -IWZFF Norman H.5aunclar'5 Oct. 14,1930. N. H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM 6 Sheets-Sheet OriginalFiled Sept. 17, 1927 N Eh EM mw Q QN Ihuen or Nur'man H.5'aundars I Oct;14, 1930. N. H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM 17, 1927 6Sheets-Sheet 5 Original Filed Sept.

D J Inventor Nur'manf-IEraundars Oat; 14,1930; N. H. SAUNDERS AUTOMATICTELEPHONE SYSTEM Original Filed Sept. 17, 1927. 6 Sheets-Sheet 4 lumen:31" Nurman H Saunders 6 Sheets-Sheet 5 N. "H/SKUNDERS Inuen or. NarmanHSaundars flwm AUTOMATI C TELEPHONE SYS 'I'EM Original Filed Sept.

Oct. 14, 1930. N. H. SAUNDERS 7 AUTOMATIC TELEPHONE SYSTEM OriginalFiled Sept. 11,1927

. 6 Sheets-Sheet 6 NormafifiSaundarl Patented Oct 14, 1930 UNITED STATESA ENT OFFICE NORMAN H. SAUNDERS, HOMEWOOD, ILLINOIS, A SSIGNOR T RESERVEHOLDING GOMPANY,.OE KANSAS CITY MISSOURI, A CORPORATION OF DELAWARE',AZU'TOMATIC TELEPHONE SYSTEM Application iiIedSepteniber 17, 1927,Serial No. 220,160. Renewed March 20, 1930.

The present invention relates in general to automatic telephone systems,more particularly to such systems in which line finders are employed toconnect an idle selecting switch 5 with a calling line; and theprincipal object of the invention, briefly stated, is the production ofa new and improved finder. switch system, the improvements tending tomake the system morereliable, to give .uniform high quality service, andto make it cheaper to install and maintain.

i The present invention relates more specifically to a searching typefinder system, in which'the' finder switches move under their own powerand control in search of a calling line. In systems of this type, twobasic groups of lines are grouped together and made first choice toionegroup of finders while 1 other subgroups are grouped together and makefirst choice to another group of finders.

' By this arrangement, a minimum travelof the finder switch is secured,and thereby the time required for the finder switch to pick up a callingline is materially reduced. In systems of this type, devised heretoforeand of which I am aware, in case of an emergency, such as an all finderbusy condition or trouble in one finder group, the preferential servicewas discontinued, that is, the remaining finder switches were calledupon to pick up calls from, the two basic line groups irrespective 40 ofthe position of those lines in the banks of the finders, consequently alonger period of time was required onan average to pickup a callingline.

As a. further object of the present invention, I provide a new andimproved distributor switch, which will maintain the.

preferential service arrangement even when the two groups of finders arethrown together as one large group and operated responsive to 9 callsfrom. either basic line group.

'- of the foregoing patent.

the needs of a. distributor switch and in ac- Further objects, notspecifically mentioned here, will be best'understood from the detaileddescription and claims which follow.

The drawings comprising Figs. 1 to 6, inclusive, when arranged withFigs. 1, 2 and 3 from, left to right in a straight line, with Figs. 4,5, and (5 right directly beneath, and withcorresponding lines inalignment, show suflicient details to enable a clear understandof Loniaxand Saunders,'No; 1,688,588, issued -Oct.-23, 1928, I am using thefinder and line equipment arrangement shown in that application. Thus itwill be seen that Figs. 1, 2 and 3 are identical with Figs. 1, 2 and 3In Fig. 1, I show a finder anda selector switch assumed to be in thegroup A, Fig. 2 I show two line equipments, the finder bank multiple andthe 'vertical banks for controlling the finder switches of group A andgroup B, Fig. 3, I show a finder and a'selector switch assumed to be inthe group B.

In Fig. 4, I show adistributor DA, through the operation of which thefinders of group A are preselected and taken for use byfcalliiig lines.The distributor DA differs from the distributors in finder switchsystems devised so heretofore, in that it employs a Strowger switchmechanism, instead of 'a rotary lineswitch mechanism, with the circuitsof that Strowger switch mechanism modified to meet 35 cordance with theobjects of the present invention. The distributor DA' is provided withtwo sets of wipers, one normally used, having: access to thefinderswitches of the group A. The other group of wipers, whichare usedunder alternate circumstances, have access'to the finders of the groupB, for a purpose which will be apparent hereinafter. Inasmuch as thegroups A and B of finder switcheswill not exceed ten switches per group,it is not necessary to use the entire Strowger switch mechanism, but itis possible to simplify that mechanism by omitting the vertical magnetand mechanical arrangements associated therewith. The switch shaftthrough the operation of which the switch room attendant may throwthetwo. groups offinders Aand B into one group,thereby permittingthedistributor DA, for example, to have access to the finder. switchesof both groups. In Fig. 6,;I showa distributorswitch DB which isidentical in structure and circuits Ito that shown in Fig. 4, the switchDB hav- -ing normal access to the finders of the group r Theo'perationof the finder switch system shown in the present invention is identicalvwith'that shown in the above mentlone'd copending application, with theexception of the operation of the distributor switches. Briefly,responsive to'the initiation of a call on the line, a preselected finderswitch is started, in the. group having first choice access to thatlinesearching in a vertical direction for the level containingthe callingline, and when that level is found, switching over and searchingina'horizontal" direction for the contacts otthe calling line. 'When thecalling line is I'found, the finder is switched through to connect itwith a selector switch, and a kick off ground is returned to thedistributor switch.

This kick oflf ground releases the distributor switch from the finderthat has just been opstated, and operates the motor magnet of thedistributor to step the wipers overthe bank contacts in search ofanother idle finder in the same group. g V

In case the finder which has just operated happens to be the last idlefinder of the group the distributor switch is not operated, since thereare no other idle finders in the group for it to find. The all finderbusy relay falls back, and the start circuit is connected through to theother'finder groups, operating totpick up calls in the first line group.

fi In case of a fault in the group B disthat group distributor tocontrol its finders l j tributor, the despatcher may hold that equipmentout of service by operating the key K t hereby'eXtending thestartcircuit of both groups of lines to the distributor DA. The

distributor under this circumstance,'operates -to find" an idle finderin the A group responfisive as the initiation of a call on an A groupriline,and' operates to find an idle finder in the thr'own that thedistributor DA has access to tlie. -find er s ofthe'group B, and thenithas accessit'o' Lthose fi nders only in response to calls :i n,th'e-:grou p Blines. The distributor preelectmanidle finder in the'groupA,"-and Bgroup responsive to the initiation of a call 4 "on a B groupline. It is only when this key is call. At springs 463 cuit from groundover conductor 477, through when it is started responsive totheinitiation of a B call, it is a post selecting distributor, that is, itpicks out an idle finder in the group Batter the call has beeninitiated.

Similarly, operating thekey in the op- 5 posite direction willdisconnectthe distributor DA, and route all callsto the distributor I DB, givingthat distributor access to the finders of group B responsiveto callsoriginating in thegroup B line, and'access to'findersof group Aresponsive to the'c'alls lnitlating 1n the group .Aline.

"Having thus" described my inventionin general, I will now proceedwvitha detailed description of its operation.

Line, swarms th am j Assuming now that the line S initiates a call, acircuit may be traced from ground at springs 211, conductor 254, throughthe hook- --switch, receiver. transmitter and calling device of thesubstation S, conductor 255,

springs 215,,through the righthandwinding of relayfZOl to battery,energizing relay 201'. At spring 213rand its break contact, relay 201removes ground from the private conductor 256, associated with the lineS and the banks of the finder switches, to render the line call ing.Relay 201. also'closes at spring'2l3and its make contact a circuit fromground;

through that spring and spring 214 to the start conductor '250,"therebyplacing ground potential upon the second bank contact ofthe verticalbankVA, and upon the ninth bank 2 contact ofverticalflbank V B, for apurpose which will be brought out hereinafter. The ground conductor 250completes a circuit through the resistance 251, conductor 260,

the spring 502and its break contact, conductor 475, through thewindingof start rela-y 409, through springs 460, to battery. Relay .409energizesfoverthis circuit to start the preselected group A finder insearch of the 1 calling line. The energization of relay 409,

'opensat spring 462a point in'the circuitof-a relay 408, to prevent theener'gization' of that relay duringthe process of setting the instantrelay 409 closes a cir springs 447 springs 457,through the winding ofrelay 406,springs 445, spring 443 and its break contact, springs 439,springs 435,

through the winding'of relay 401 to battery.

\ Relay 406 energizesiin this circuit, but be- 1 cause of the high"resistance ofthat relay,

relay 401 does not energize at this time. The

energization of relay 40G, closes a circuit from ground through spring453, through the winding of all finders busy relay'405, to maintain thatrelay energized throughout the setting of the instant call even thoughthe insta-nt call may use the last idle finder in the group A Belay 406,at s'pring 454 closes a circuit from ground on. spring 458 throughthesupervisory lamp 412 and the slow alarmdevice, not shown, to battery.The lamp 412 lights to indicate a call is being set by the tindercontrol by distrilouiorv DA, and the slow alarm device is startedoperating. This dev which n ay be any well lniown slow C '='cuit of theslow alarm losed for longer than a s will operate, to call the s r sattention to the trouble, neiay 406 at springs opens a point in theall-iinders busy circuit of the group B, for a purpose which will'beexplained hereinafter, At .spr 4.51, relay 406 opens a point in thecircuit of wiper 427, to prevent the op ation of the distributor DA overcircuits controlled through that wiper until the present call hasbeen'set. At springs 450, relay 406 closes a circuit from ground th.augh resistance 4 is, springs 455, springs 450, wiper 425 new inengagement with the ntact to which conductor 163 is connect-ed, jiector163, negative trunk conductor 150, spring 117 of the selector EA, tin"lgll the upper wig of line relay 1.02 of the selector EA to battery.Theline relay 102 energizes overthis circuit, and springs 116 K sthe-obvious circuit tor l e release relay 101. .he release relay101encrgizes, and at springs 113 places ground on release trunk conduc-151, for a purposewhich ill be explained hereina :er. Relay 406 uponoperating prn fi l-49 closes a circuit from ground thro ,i the wiper 424now in engagement with the contact to which the conductor 162 isconnected, tlj roughthe conductor, sp i 125 and its break contact,springs 121, sprin 120, through the windingof stepping relay 107 of thefinder FA to battery. Relay 107 energizes over this circuit, to, startthe f: er FA in operation.

Operation of finder FA The operation of the finder in the presentinvention is the same as that described in detail inthe above mentionedpatent, and for that reason will only be briefly described in thepresent specification. Responsive to the energization of relay'107, acircuit is closed from conductor 162 through springs 129, spring 124 andits break contact to the windingof the vertical magnet 125'to battery.The vertical magnet energizes over this circuit, elevates the shaftcontaining the wipers of the finder FA one step, and opens the springs121, to open the previously circuit for the relay 107. Relay 107 fallsback, and spring 129 opens the circuit just traced for the verticalmagnet 105. This interaction of relay 107 and magnet 105 contin'ues aslong as the vertical wiper 262 of the tinder FA fails to pick up groundpoten tial, Since the Calling line S has a finder 250, the second bankcontact of the vertical bank VA, wiper 262, conductor 158-, through the,upper winding of relay 106, springs 120,

through the winding relay 107 to battery. Re

lay 106 energizes over this circuit, and relay 107 which was inenergized position when the circuit was closed, remains in its energizedposition. The energization of relay 106 transfers the impulsing circuitfrom the vertical to the rotary magnet, that circuit being closedthrough springs 129 andspring 124 and its make contact, through thewinding of magnet 104 to battery. The rotary magnet 104 energizes, andmoves the shaft containing the wipers of the finder FA one step in therotary direction, and opens at springs 120 the above traced circuitforthe relay 1 07. Relay 107 falls back, opens the circuit for magnet104, permitting that magnet to tall back and again close the circuit ofrelay 107. Assume now that the first contact in the sec- 0nd level isthe contact of an uncalling line, the test wiper 234 will pick up groundpotential, completing the circuit through conductor 157, spring 122,spring 132, through the wiper switching relay 109 to battery. Wiperswitching relay 109 energizes overthis circuit, at spring 138 connectsthe test Wiper 231 through conductor 156, springs 138, springs 131,spring 125 and its make contact, spring 121, spring 120, through'thewinding of relay 107 to battery. If the test wiper 231 is engaging anuncalling line, relay 107 energizes over this circuit, again closing acircuit for the rotary magnet 104 which energizes and advances thewipers another step. This interaction of relays 107, 109, and 104continues until one of the other of the test wipers 231 and 234, engagesan ungrounded contact associated with a calling line. During thestepping of the switch FA, the switch through relay 108v has been shortcircuited, ground being applied to the upper terminal from the releasetrunk conductor 151, and to the lower terminal from spring 127 whenrelay 107 is energized, and from conductor 156 through springs 138 and131 when relay 107 is deenergized. Since the line'S appears in the banksto which Wipers 233 to 235, inclusive, have access, wiper 234 will loseground potential when the contacts grounded contacts,

through the winding of the relay 108, spring 125 and its make contact,spring 121, spring 120, through the winding ofrelay 107 to battery.Because of the'high resistance of the Distributor DA searches forz'rtlefinder The ground placed upon conductor 164 by springs 135 completes thecircuit for relay 407, traceable through wipers 426, springs 442,through the winding of relay 407 to battery. Relay 407 energizes, and atspring 457 opens the circuit previously traced for relay 406. At springs458, relay 407 opens the cir cuit previously traced through the alarm'lamp 412 and the slow alarm device, to deenergize those devices. Thedeenergization of relay 406, closes a circuit froiniground throughoff-normal springs 140 of the finder F A, conductor 165, wiper 427 ofthe distributor DA, springs 451, springs 445, spring 443 and its breakcontact,-springs 439', spring 435, through the winding of relay 401 tobattery. Relay 401 energizes over this circuit, and at spring 431prepares a locking circuit for itself, that circuit including theinterrupter springs 435. At spring'430, relay 401 closes the obviouscircuit for the rotary magnet 410,,

causing that magnet to energize and advance the wipers one step. If thenext finder of the group A is busy, the wiper 427 will pick up groundpotential, reclosing the previously traced circuit for relay 401, whichagain energizes, locksitself through the interrupter springs, and closesthe circuit for the rotary magnet 410, energizing that magnet to causethe wipers of the switch DA to be moved on to the next contact set. Thisprocedure will continue as longas the wiper 427 encounters finders. Whenan idle finder is encountered, the wiper 427 will fail to pick upground, and the finder DA will come to rest upon the contacts associatedwith that finder, preselecting it in readiness for the nextcall.

, The Strowger switch mechanisms, such as is used for the distributor DAhave a normal capacity of ten contacts in each row, so when the wipers420 to 427, inclusive, have been stepped ten steps it is necessary torelease them and to return them to their normal positions beforeadditional steps can be taken. F or this purpose the cam spring 437 isprovided. and after the wipers have been stepped off of the last contactin-their banks, that is after the eleventh step, cam springs 437 close,

associated with busy closing a circuit for the relay 403. Relay403energizes, and at springs 440 locks itself through off normalsprings436, thereby 1nsuring that it will remain in its energized closessprings 441, thereby closing a circuit for the release magnet 411 toenergize that magnet. The release magnet upon energizing withdraws theholding pawls from the shaft, containing the wipers 420 to 427, therebyreleasing the distributor DA to normal in the well known manner. Thewipers of the distributor DA are mounted on a shaft in such a positionthat when the shaft is in its normal position, the wipers will encounterthe first contact set in the bank, rather than encounter no contacts asis customary in a V Strowger switch. The oii-normalspring 436 opens justbefore the switch reaches its normal position, to unlock the circuit ofrelay 403, to permit that relay to restore an'd open the'circuit of therelease magnet and prepare the circuit of the stepping relay 401. If thefirst finder of the group, upon whose contacts the distributor wiper 427will pick up aground potential, and the circuit of relay 401 will becompleted, energizing that relay to step the distributor DA off of thatconta'ct'set. The testing operation will continue until an idle finderis found, at which time wiper 427 will lose its DAis now resting, 1sbusy,

ground potential and the distributor will i come to rest. I

Line 8 initiates a call ances, in this case resistance 253, to completea circuit for relay- 601 of the distributor,

DB. Relay 601 energizes over this circuit. opening the circuit of'relay602 at spring 630, and closing a circuit for the start relay 601 atspring 631 traceable from ground through those springs and spring 647 ismake contact, springs 637, through the winding of relay 604, springs'645,'spring 615 and its break contact, interrupter springs 659, relay609 to battery. Relay 604 energizes over this circuit, and, because ofthe resistance of that relay, relay 609 is prevented from opera ating.The energization of relay 604 c'loses the alarm circuit'at springs 644;closes a holding circuit for all finder busy relay 605 at springs 643;opens a point in the testing circuit at springs 641'; opens a point inthe all finders busy-circuit of the group A at ing a circuit throughsprings 338, springs 350,- springs 349, conductor 370,.through thewinding of relay'303ofthe finder FE to battery. Finder FBoperates, firstin a vertical direction to find the -level containing the calling'line,and'then in'a horizontal direction to find the calling line, and at theend of that operation switch through relay 302 energizes to connect thecalling line with the idle select-or. The energization of relay 302closes springs 330,,thereby placing ground on conductor 374, that groundbeing picked by wipers 621 to complete a circuit through springs=649 andthe winding of relay603=to'battery. Relay'603 energizes, and atsprings635 opens the circuit over which relay 309 of the selector EB wasinitially energized, to prevent the resistance ground from interferingwith the operation of that relay during impulsing. Belay 603, at springs637 opens a point in-the circuit of relay 604, permitting that relay todeenergize. "t spring638, relay 603 opens the circuit thro'ugh the alarmlainpiand slow alarm device to prevent fu'rther operation of thosedevices at this time; 'Relay604, fallsback, and at springs 641 completesa circuit for the stepping relay' 609, that circuit being trace- I ablefromqground through ofi norn al spring 303 of the finder FByconductor 373, wiper 620, springs 641, springs 645, springs 650, springs 652,interrupter springs 659, through the winding of relay 609 to battery.Relay 609 upon energizingycloses springs 662, therebyconipleting alocking circuit for-itself in series with interrupter springs 659. Atsprings 661 relay 609-closes the obvious circuit for the rotary magnet610, energizing that magnet to advance the wiper-s 620 to 627 52. oftlie' distributor DB one step, The operatron ofithe rotary magnet opensthe circuit of relay609, permittingthatrelay to deenergize to open thecircuit of the rotarymagnet.

Iflthenext finder of the group is busy,.wiper 620 cagain finds groundpotential and the sanie cycle of operations' is repeated,continuing-untilthe wiper-620 encounters an "ungrounded contactassociated with an idle,

finder. VVhen eleven stepshave been taken 3 by theqrotary niagnet, camsprings-660 oper ate,zclosing a circuit for relay 607, which energizes.Relay 607 looks itself to springs 653 through off-normal spring 659, toinsure that it=willreniain in-an energized position until"thedistributor DB returns-fto-its normalpo- Allfinders busy conditionAssume now that all the finders in group A becoinebusy, when thelastfinder of the group goes oii norinal, ground is removed from theall-finders busy, conductor 161 at oft-normal springs 126 ofthat'finder,thereby opening the circuit for normally energized relay 4050f thedistributor 'iDA. 'This relay falls baclgand at .springs 445 opens apoint in the testing circuit through wiper 427 and relay 401,- toprevent aneedless operation of the distributor DA. At springs 447, relay405 closes a point in the start circuit, icontrolled by relay'409, sothat responsive to a call in'the A group of lines, aB finder will bestarted. When relay .409is energized responsive-to the initiationofacallon a group A line, it closes springs 4'63, thereby closing a circuitfrom ground over conductor 477 through spring 447 and its 'brealrcontact,

conductor 478, springs'647 of the distributor DB, springs 637, throughthe Winding of relay 604, hence over the previously (traced circuit torelay 609 to battery. Relay 604 energizes over this circuit, to start.the finder 1 y switch preselected by the distributor DB to operating inthe usual manner. Since the calling line S appears in the upper half ofthe bank ofthe finder switches of group B,

take niore than five steps, in'this case nine steps, to reach'the levelcontainlngthe callingline. The operation of the finderiunder thiscircumstance'is identical to that already explained and will not berepeated at this time.

' Similarly if all the finders in the groupB become busy, all finderbusy relay 605 is deenergized wheuthelast finder of ,thegroup is taken{for use and ground is removed from 1;=

itwill be necessary that theselectedfinder DA, s prings457, relay 406,thence overthe 446, conductor 47 3 to the all finder busy common 161,and the other from that commonthrough conductor 47 3 and the springs 642of the relay 604 ofthe distributor DB,conductor 510, springs 501, thencethrough the conductor472' to the relay 405. Itwillbe noted thatwhen-therelay once falls back, the ,directilocking circuit to the all findersbusy common is broken at springs 446 and that'the parallel path for therelay'405 is open whenever the relay 604 of the distributor DB isenergized. It then, while the distributor is sending a callfrom a linein either group, a finder in the group Abecomes idle thereby placingground on conductor 161, all finders busy relay 405willnot be ener gizedimmediately but rather will remain deenergized untilthe relay 604 of thedistribus tor DB restores at the completion otthe setting of the call;By' this arrangement, the idle finder in thegr'oup A is prevented fromstealing the call from a group B finder. If it werenot for thisprovision, if the group B finder were setting a call in one'of the lowerlevels of the A line group, which levels appear as the uppermost levelsof the'group B finders, a finder in the A group becoming idle after thegroup B finder has beenstarted, might be started and connected with thecalling line before the group B finder would reach the contacts o'fthecalling line, thereby causing an unnecessary operation of the" groupBfinder. By holding'the all finder busy relay 405 open until thedistributor DB comes to rest at the end of a call, this steal- 7Similarly the all finders relay 605 of the distributor DB} ing of a callis preventedl is maintained energized over twocircuits one ofwhich isbroken when I by spring 452 of the relay'406, of the distendant maytributor DA, this similar arrangement piefrom I an A venting thestealing of a callgroup finder bya B group finder. v

The operation, 0/ 7063 K7 is It may happen that because of some troublein one of the distributors, the switch room atfind it advisable toremove that distributor from service forrepairs To do this he operatesthe keyK which'alters the start circuits so 'thatcalls from both linepresent time. the relay fall's back at springs 646, and the other heldopen' anew . groups are handled by the'one remaining distributor,.whichselectsan idle finder in accordance with the group containing the linewhich'originatedthe call. Thatis when one distributor, for example DA,is handling all of thetrafiic in the two line groups, callsoriginatingin-the A line group will be handled by a finder in the Agroup, if there is an idle finder inthat group, and calls originating inthe B line group willbe handled by-a group ,Bffinder, ii there is anidle finder in that group. It will be noted that the bank contactsaccessible to the wipers 424 to 427 of the distributor DA are'multipliedto the bank contacts accessibleto the wipers 624 tov 62? inclusive, ofthe distributor DB.- Similarly the contacts accessible to: the wipers420 to 423, inclusive, ofthe distributor DA, are multipled with thecontacts accessible to the wipers 620 to 623 of the distributor DB.Inthe normal course-of operation, wipers 424 to 427 of the distributorDA'are the wipers used,and;

have direct access to the finders of the group V the distributor DB arenormally used and havedi rect access to the finders of the group, B.When the key is thrown, the wiper sets to be c A. Wipers 620. to 623,incliisive, of

used by thedistributors,depends upon the startrelay energized by theinitiation of a call. That is each line group start wireterminates-inadilierent startr'e'lay in the distributor, so that when the A groupstar-tree lay is energized, the distributor selects-'aniidle finderin'the'A group from its no'rmal set of wipers lVhen the B group startrelay is energized the distributor selects a finder in the I B groupthrough its alternatesetof wipers. 7 Assume" now that the attendant,operates key K tothe left to operate springs 501 and 502. This operationremoves the distributor DA from service, and routes the' calls to thedistributor DB. The operation of spring 501 away from its break contact,opens the group busy common-161 from the. all finder busy rclay 405 ofthe distributor DA, permitting said relay to restore to normal. The busycommon conductor161 is now connected through spring 501 and its makecontact, conductor 512, .to the spring 632 of theirelay 602 in thedistributor DB, this spring being open at the 1 The operation ofspr'ing502 disconnects thestart wire 260from the group A and connects itto conductor 514' leading,

I through springs630 to the relayv602 of the distributor DB, When a linein the'A group initiates a call and'places ground on the startconductor260,'relay 602isenergized; At

springs 632, relay 602 extends the alL-finder I busycommon ground. ofgroup A through i those springs to, .thewinding of relay 606,1completing a circuit forthat relay to energize.

it. 7 At springs 633, rel cuit of relay 601,so that a call originatingin the'B' group will have to wait untilthe dis-' tributor DB hasfinished with the instant call.

ay 602 opens'the cir-* i V D springs 659 through the Winding of relay609 to battery. It will be remembered that in the foregoing descriptionof the operation of distributor DB the control of the distributor Ywhensearching for an idle. finder is through thewiper 620,which operated thedistributor until that wipertound an ungrounded contact, associated withanidle finder in the B It may happen therefore that the wipers oi thedistributor DB atthis time are standing upon the contacts of a busyfinder in the A group, in which case wiper 627 will pickup aground'potential, which is projected through springs 65Tto the upperterminal of relay 608. If this is the case, relay 608'will not energizeimmediately but will be short circuited, and relay 609 will energizefrom the direct ground picked up by wiper 627 and applied to the circuitof relay 609 at a point excluding the winding relay 608. Relay 609, uponoperating, closes the circuit of the rotarymagnet as hereinbetoredescribed, to step the Wipers of the distributor DB in search of an idlefinder in the A group. ."When that finder is found, wiper 627 loses itsground potential and. the short circuit is thereby removed from relay608. Relay 608 then energizes through relay 609. -Itelay 609 does notpull up to again close the circuit of the rotary magnet, because of thehigh resistance of the winding of relay 608'. Relay 608 upon pull ingup, opens at springs 65'? the testing circuit through wiper 627, so thatthe distributor DBWill not st-ep otf theselected finder when the guardconductor of that finder is grounded. At springs 658, relay 608, closesa circuit from ground through spring638 to the alarm lamp and slow alarmdevice, for the purpose which has been previously described. At springs656, the relay 608 closes a circuit from ground through resistance 613,spring 635,

I spring 656, wiper 625, conductor 163, conductor 163, trunk conductor150, spr ng 117,

through the upper winding of the line relay 102 of the selector EA,energizing that relay to seize the selector and finder in the mannerhereinbetore pointed out. At springs 655, relay 608, closes a circuitfrom ground through wiper 624 to the start conductor 162 which is,eonnected through "startconnector 162 of the finder FA, that groundoperating the relay ql07 to start the finder in the nianner'hereinbeforepointedout. The finde'rFA now opcrates in the manner which has alreadybeen described,finally positioning its w pers upon the contacts of thecalling line and energizing relay 108 through the establishedconnectiontherewith; At spring 135, the kick off ground is applied to conductor164 as bet-ore, ground now being picked up by wiper 626, completes acircuit through spring 649 and its make contact, through the winding ofrelay 603 to battery. Relay 603 energizes, and at spring 638 opens thealarm and signal circuits to prevent further operations of those devicesat this time. At springs 637, relay 603 opens a point e in the circuitof relay 604, however since that relay is not energized this operationserves no useful purpose. At spring 636, relay 603 opens a circuit ofrelay 608, permitting that relay to fall hack to normal. The restorationof relay 608 closes at springs a point in the circuit of the distributorDB through which that distributor seeks an idle finder in the A group.it another call is waiting in the A group, conductor 260 will be stillgrounded,

and sta t relay 602 will remain operated. Relay 606 will also remainoperated if there is an idle finder in the group A, and the distributorDB will test through wiper 627 to connect with that idle finder. Ifhowever the instant call was the only call pending in the group A, relay602 deenergizes when the cut oil relay 202 of the calling line isoperated, because that relay removes ground from the start conductor260. Relay 606 Will thereupon be deenergized, and the distributor DBwill test for an idle finder in the B group under the control of thetesting circuit through wiper 620, in the manner already pointed out.

Thus it will be seen that When the key K is operated, calls in the Aline group are handled by an A group finder under the control of thedistributor DB. Since the operation of the key K has no eil'ect upon thehandling of a line call by a B finder under thecontrol of the Bdistributor that operation will not be repeated at this time. 7

If there are no idle finders in the A group at the time the key K isthrown, vconductor 512 will not be grounded, therefore when reoperatedover a circuit through spring 631 of the start relay 601. The B finderwill pick up the A line code, making more than five vertical steps toreach the level containing the calling line.

If the key K is thrown to the right to operate springs 504 and 505 thedistributor D13 is removed from service and all vcalls are handled bythe distributor DA. The operation of spring 504, opens the circuit fromthe busy common conductor 367 to permitthe relay 605 to tall back. Theoperationot springs 505 extends the groupB start conductor 261 throughthose springs to conductor 476, preparing a circuit through springs 462and relay 408 tobattery. When a group '13 line operation ofspring 594extends the all finder busy common. 367 through conductor 474 therebypreparing the ClTCUltWlllCll is com-- pleted when relay 408 energizes toenergize 1 the relay 404. Relay 404 transfers the con trol of thecontrol of the distributor DA from the normalset of wipers to thealternate wipers 420 to 423, inclusive. 7 If the wiper 420 is standingon the contacts of a busy finder, a circuit for relay 401 Will-becompleted through that Wiper, springs 484, spring 443 and its makecontact, spring 439, interrupter spring 435 to the winding relay 401 tobattery. Relay v401 will energize, lock itself, and close a circuit tothe rotary magnet 410. The rotary magnet willadvance the wipers and-openthe circuit of relay 401, this interaction of the magnet and relaycontinuing until wiper 4 20 encounters an ungrounded contact. Relay 402'will then be energized from ground through springs 4610f the 408, spring444 and its make contact, spring 456, through the Windin ofrelay'402,spring 443' and its make contact, springs 439, through the interruptersprings 435,through the winding of relay .401zto battery. Relay 402; atsprings 438, closes a circuit for the signal alarm lamp and the slowalarm device;

at spring 434 opens a point inthe circuit of the wiper 420 to insurethat the circuit of DA will not step-elf of the contacts of thepreselected finder when that finder is made busy by the present call: Atsprings 433, re-

lay 402'closes a circuit from ground through resistance-414, springs455, through the wiper 420 through the conductor 375,to seize the linerelay of the selector EB in the manner hereinbefore pointed out;"Atspring 432, relay 402 applies ground through the wiper 423 andconductor 376 to the start conductor 876,

ofthe finder FB, to start that finder operating in search of the callingline. When the finder P13 is on the calling lineand relay802.

is energized, kick off ground will be placed on conductor 37 4 by thesprings 380, that ground being picked up by the wiper 421 to completethe circuit through spring 442 and its make contact through the relay.407 to bat tery. Relay 407 energizes to restore the distributor DAtonormal and'to complete the circuit preparatory to selecting anotheridle finder. If there is another idle finder in the B group and anothercall waiting in the B line group, the selectionwill be through the wiper420,- and will be ace manner/just pointed out The. operation of thekey Kdoes not in any way elfect the control of the distributor omplished inthe .DA by a call in the A group so that operation will notbe repeatedatthis time.

Having thus described my invention, what; I conslder new and desiretohave protected by Letters Patent is pointed out in the appendedclaims.

What is claimed is 1. In a telephone system, subscribers lines adistributor switch having a plurality of 'wi ers a ou 'of contact setsaccessible to each of sald wipers,a finder switch assooiated with eachofsaid contact sets, a trunk line individual to each finder, means in'thewipers have been stepped ofi, the last contact set of the group forreleasing them and returning themto the first contactset, and

means for stopping said wiperswhen'an idle finder is found. T

2. In a telephone system, subscribers"li'nes,- a group, of finderswitches,.a trunk line individual to each finder, means in the finderfor connecting the individual trunkline to a calling one jof saidsubscribers lines, a distributor. switch-having a'plurality ofpositions'corresponding to said finders, meane for operating S2116].distributor from posi tion'to position .to test. the busy or idle con- Hdition of said finders one at a time, and means in said distributor,operated after the last finder of the" group has been tested,'for

releasing said distributor and returning, it

to the position from which it teststhe first V 10o 8. In a telephonesystem, subscribers lines,

finder of said group.

a, group of finder switches, a trunk line. in-

dividual to each finder, means in the finder for connectlng theindividual trunk line to .a calling one of .said' subscribers lines, a

distributorswitch having a plurality of positions corresponding to saidfinders, means" for operating said distributor from position :toposition to test the busy or idle condi tion of said finders one atatime, means in said distributor, operated after the last find-, er ofthe group has been tested, for releas ing said distributor andreturning-it to the posltion from which it tests the first finder ofsaidgroup, and means for preventing the performance of said testlng whilesaid dis-f tributor is returning to said latter position, f

Inga telephone system, a distributor switch havingwlpers, a group.of-fincler switches aceessiblethrough normal onesof said wipers; asecond group of finders'accessible through alternate ones of saidwlpers, means 1n sa d-distributor operated through said: normalwipe'rs'top'reselect an idle finder in the group. accessible through thenormalwipers, a ke'y, means responsive tothe operationof said key forconditioning sa d first means for operation through said alternatewipers, and means responsive to a' callfor operating said first'means toselect use the alternate Wipers.

5. In a telephone system,,a plurality of 'groups'of lines, a pluralityof groups of finder switches having access to said lines, adistributorswitch for each of said finder groups and normally operatedtoselect idle finders in that group, means forgiving said distributorsaccess to the finders ofthe other finder group, means 'lor combiningsaid lines into one glOlltp byarcinoving one of said distributors fromservice and means then responsive to the initiation'of a call on one ofsaid lines for'operating said other distributor to select and start afinder in the group having access to that line.

i 6. In a telephone system, a first and a second roup of lines, a firstand a second 'roup of finders having access to said lines respectively,first and second distributor switches for allotting said finders foruse, means responsive to the initiation 01" a call on a line of thefirst group for operating said first distributor to start, a preselectedfinder or the first group in search of said line, means for giving saidfirst dis ributor access to said second group finders, means responsiveto the initiation of a call on a line in said second group to start saidfirst distributor in search of an idle finder in said second group, andmeans in said first distributor operated responsive to the finding ofsaid second group finder for starting it in search of said calling line.

7. in a telephone system, a first and a second group of lines, a firstand a second group of finders having access to said lines respectively,first and second distributor switches for allotting said finders foruse, .icans rcsponsive to the initiationot a call on a line of the firstgroup for operating said first distributor test-art a preselected finderoi": the first group in search of said line, means for giving said firstdistributor access to said secoud group findergmoans responsive to theinitiation of a call on a line in said second groupto start said firstdistributor in search of an idle finder in said second group, means insaid first distributor operated responsive to the findingof said secondgroup finder for starting it in search of said calling line, and meansin said firstdistributor responsive to the finding of said second groupline for opcrating said distributor to preselcct an idle finder of saidfirst group.

8. In a telephone system, a first and a second group of lines, a firstand asecond group of finders having access to said hnes respectively,first and second d1str1butor switches for allotting said finders foruse, means responsive to'ithe initiation of a call on a line of thefirst group for operating said first distributor to start a preselectedfinder of the first group in search of said line, means for giving saidfirst distributor access to sand second group finders, means responsiveto the initiation of a call on a line in said second group to start saidfirst distributor in search of an idle finder in said second group,means in said first distributor operated responsive starting it insearch of said calling line, and means in said first distributorresponsive to the finding of said second group line for operating saiddistributor to select another idle second group finder if another linein that group has initiated a call meanwhile.

9. in a telephone system, a first and a second group of lines, a firstand, a second group of finders having access to said lines respectively,first and second distributor switches for allotting said finders foruse,means in said distributors for preselecting idle finders in theirrespective groups, means for giving said first distributor access tosaid second group lines, and means responsive to said last means formaintaining said distributor preselecting With respect to said firstgroup finders and post selecting With respect to said second group linesand finders.

10. In a telephone system, a first and a second group of lines, a firstand a second group of finders having access to said lines respectively,first and second distributor switches for allotting said finders foruse, means in said distributors for preselecting idle finders in theirrespective groups, means for giving said first distributor access tosaid second group lines, and means responsive to said last means formaintaining said dis-- to the finding of said second group finder for itributor preselecting with respect to said first group finders and forstarting it in search of an idle finder in said second group responsiveto the initiation of a call by a line of said second group. I I

' 11. Ina telephone system, two groups of telephone lines, group offinder switches for each of said line groups, a distributor switch foreach finder group, each distributor having access to the finder of itscorresponding group through normal wipers and to the l finders of theother group through alternate ipers, means in said distributors -forpreselecting idle finders through the normal wipers, a relay in saiddistributors, a start Wire for each line group terminating in the relayof the respective distributor, means responsive to the initiation of acall on one of said lines for ener izing said relay over said start Wi eto st the preselected finder of the corresponding group, a key, a seconorelay in said distributors. means responsive to the operation of saidkey for disconnecting one of said start wires from its relay and connecting it to the second relay oi the other distributor, meansresponsive to the initiation of a call on one otthe lines associatedwith said. one start Wire for energizing said second relay and meansresponsive to the venergization of said second relay for ope-rating saiddistributor to select and start a finder throu hits alternate Wipers.

12311 a telephone system, subscribers lines, agroupof finders havingaccess to said lines, a-distributorswitch having a plurality of Wipers,a groupot contact sets accessible toeac'h ot said Wipers through whichcontats said distributor has access to said finders, means responsive tothe initiation of a call on one of said lines for operating one of saidfinders to establish a connec tion with said line, means for making eachof said finders busy-to said distributor, means responsive to theestablishment of said conncction for stepping said Wipers over saidcontact sets in search of an idle finder, means operated-after theWipers have been stepped off the last contact set of the group forreleasing them and returning them to the first contact set, and meansfor I stopping said Wipers When an idle finder is found.

13. In a telephone system, a plurality of "choice access, means forremoving one of said distributors from service, means then operatedresponsive to a call on one otsaid lines for operating'said remainingdistributor to select and operate a finder of the group having firstchoice access to said line to establish a connection to that line.

14', In a telephonesystem in Which subscribers lines are arrangedingroups which are preferentially served by groups offin-ders eachcontrolled by a. distributor individ ual to that group, means forremoving one of said distributors from service and'tor thereby givingthe other distributor access to all finders, and means in saiddistributor responsive to the initiation of a callon a line forselecting and operating a finder Which gives preference to the groupcontaining that line to establish a connectionvvith that line.

15. 111 a telephone system, adistributor switch having a connected setand a disconnected set of Wipers, a' group of findersaccessible throughsaid connected set of Wipers, a second group of finders accessiblethrough said disconnected set of Wipers, means in said distributor foroperating the normally-connected set of Wipersto preselect an idlefinder in the first group, akey, means responsive to the operation ofsaid key for preparing said 7 normallyrdisconnected set of Wipers forconnection, and means responsive to the initiation of a call onone'ofsaid lines for comisaid lines to start such third finder pletingthe prepared connection and for op erating said distributor to selectanother idle finder through said normally-disconnected Wipers and'tostart such othe r'find'er to find the calling line. 7 Y a 16. In atelephonesystem, a group of lines, a group'of finders having access tosaid lines, a distributor having access I to said finders, meansresponsive to a call'on one of said lines for operating said distributorto start a preselected finder in search of the calling line, meansinsaid distributor responsive to'the finding of said line for operatingsaid distributorto, preselect another idle finder, means for changingsaid distributor from a preselecting distributor to a post-selectingdistributor whereby said distributor searches to the initiation ofa callon a second one of the second calling line. 17. In a telephone system,agroup ofsubscribers lines, finders having access to said lines, adistributor having access to said find-' ers, means for operating saiddistributor to preselect an idle one of said finders, and

means responsive to the initiationofa call,

on one of said lines for operating said distributor to select anotheridle finder and to start such other finder to find the calling line.

' 18. In a telephone system, a group of subscribers lines, findershaving access to said lines,- a distributor: having access to saidfinders, means for operating said distributor to preselect an idle oneof said finders, and

means responsive to the initiation of a call on one of said lines foroperating said distributor from connection With said preselected finderinto connection With another idle one of said finders and to start saidother finder to find the calling line.

In Witness whereof, I hereunto subscribe my name this 13th day ofSeptember, A, I).

NORMAN H. SAUNDERS.

'for a third idle one of saidfinders responsive lit)

